Simplified Explanation Of A Solar Water Heater Working Principle

solar water heater working principle

Solar Water Heater Definition

A solar water heater is a device that uses solar energy to produce hot water. Additionally, standard solar water heater comprises a solar collector fixed on a building roof and connected to a water storage tank. Further, the cold water will be circulated through the collector from the tank to be heated directly by solar energy.

The water can also be heated using a high-capacity heat exchange fluid warmed in the solar collector and transmit the heat to the water in the tank through tubes. While the heat transfer to the cold water from the solar collector can be done without mechanical means, you will need electricity in active solar water heater systems to distribute the heat exchange fluid and run controllers and mechanical pumps.

The working principle of a solar water heater
Solar water heater working principle. Hvatum at en.wikipedia, CC BY 3.0

Solar Water Heater Working Principle

Previously solar water heaters were large black containers. They were painted black since black is a good conductor of heat and gets heated quickly. Consequently, the water in the container would get heated as the containers get heated with the sun heat.

The method was simple but time-consuming. So, with technological advancement, new solar water heaters were developed. They work under the same principle as the traditional heater, but their systems are more complicated. The system includes anti-freeze valves, temperature gauges, insulated storage tanks, pumps, and a solar collector.

This is How a Solar Hot Water Heater works:

The sun rays fall on the solar collector made of a black surface absorber that grasps solar radiation. The solar collector then passes the heat energy to the water flowing through it.

The heated water is then collected in an insulated storage tank to avoid heat loss. Further, the circulation of water from the storage tank through the solar collector to the shower or faucet and back to the tank will progress automatically.

Solar Thermal Collector Types

  • Solar Flat Plate Collector

The flat plate collector consists of copper tubes fixed to a flat absorption plate. Indeed, the standard configuration is a sequence of parallel pipes fitted by two pipes on each end; outlet and inlet. The flat plate collector is ideal for commercial or residential projects.

  • Solar Heat Pipes

The solar heat pipes are the most effective collectors. Each vacuum pipe or tube is made like a thermos flask. The pipes containing heat-conducting fluids or water are enclosed by large glass tubes. There is a vacuum space between them, so the fluid has minimal heat loss. Solar heat tubes work well at below 40 degrees temperature and on cloudy days.

Passive, batch solar water heater
EERE, Public domain, via Wikimedia Commons

Types of Hot Water Circulation Systems

There are four different types of hot water circulation systems.

  1. Active Circulation System. Electric pumps, valves, and controllers force water from the collector to the storage tank.
  2. Passive Circulation System. As the water heats up, it automatically moves to the storage tank from the collector. This process is enabled by convection and does not require an electric pump.
  3. Direct circulation system. In a direct circulation system, water is passed through solar power collectors, where it is heated by energy from the sun. This system is ideal for places where there is no snowfall.
  4. Closed-loop Circulation System. Non-freezing liquids are stored in collectors in this system. The energy from the sun will heat this liquid that passes through the heat exchanger in the storage tank. The process circulates heat to the water in the tank from the non-freezing liquid. This system is ideal for cold places or places with snowfall.
Solar hot water heater on a rooftop of a house.
Solar water heater on a rooftop. Martinvl, CC BY-SA 4.0

Solar Water Heater Installation

Solar Water Heater Installation is more complex than a standard water heater. The following are the steps involved in the installation.

  • Mount the solar panel on the roof
  • Adjacent to the standard water heater, install the heat exchanger and the solar storage tank.
  • Install the pump and the piping
  • Fix the water piping
  • Fix the controls
  • Fill the system
  • Insulate the glycol lines and water.

The solar water heaters are cheap and environmentally friendly, making them great for residential and commercial use. They also have low maintenance since they don’t have moving parts.

Solar water heaters are available in different sizes and watts that determine the amount of water they can heat. The bigger the panel, the more the quantity of hot water it will be able to heat throughout the day.

The most common solar panel size is around 32 inches x 32 inches and can produce approximately 10 gallons of hot water per day in hot weather. Solar panels are usually glass or plastic, but some panels have a metal frame. The metal frame is suitable for commercial use since it is more durable and withstands heavy weights and pressures.

Read More: What is a Solar Power System?

Choosing a Solar Water Heater for Your Residence

Residential houses are usually fitted with different sized pipes that require different sized solar panels to work correctly. For instance, if your house has a lot of pipes, you may need more than one solar panel to cover all the pipes with hot water. The panels are connected to a solar water heating system, which heats the water and makes it flow through the pipes.

To get the most out of your solar panel, you should purchase an inverter. An inverter can convert alternating current (AC) power into direct current (DC) power so that your photovoltaic (PV) panels can work at their maximum potential.

Another thing to consider when buying a solar panel is how much space it takes up. The size of the solar panel is directly proportional to the amount of space it takes on your roof or on the ground where you install it. And so, if you have a lot of space for the panels, your investment in them won’t be as expensive as those with little space.

Why is Solar Energy Popular?

Solar energy has become increasingly popular for many reasons:

  • It’s free. Solar energy has no fuel costs and can help reduce our carbon footprint.
  • It’s environmentally friendly. Solar energy helps reduce pollution from fossil fuels.
  • It’s a sustainable energy source.
  • It’s a renewable energy source.

Solar Water Heater Buying Guide

A solar water heater saves your monthly energy bills. If you are in a market to get one, some research and shopping around are crucial. Therefore, before selecting your option, you should consider the following.

1. Evaluate Your Site

The majority of solar water heaters are fixed on the roof. For remarkable outcomes, your roof should:

  1. Be able to receive direct sunlight during the day
  2. Face south
  3. Be firm with the thatching in good condition

Also, it would help if you evaluated where you live. Most solar heater systems are designed with an expected hot water output for a particular climate. In the warmer areas, you can create a lot of hot water from a small system. In colder regions, you will require a large collector and possibly an active system to fulfill the home’s hot water needs.

2. Decide the Type of System You Need

A sound system should meet your lifestyle and needs. Also, keep in mind that a solar water heater expert can assist you in establishing what size and system suit your needs.

3. Contact a Solar Water Heating Manufacturer or Contractor

You may look for a local contractor who can access your site, give recommendations, fix the system, and maintain it. Fixing solar in an already existing house needs careful installation, which entails running pipes through walls.

4. Determine Your Budget

Solar water heaters for commercial or residential use are more affordable and have a high return on investment. However, before purchasing, get the exact cost of your plumber to ensure no hidden costs.

5. The Amount of Water you Need to Heat

Your lifestyle greatly impacts how effective your solar heater will be. If you have a high demand for hot water or have a large family, you will need an active system with a vast collector to satisfy your family’s needs. In contrast, a passive or smaller system may be ideal if you only have one or two people in your household and infrequent laundry activities.

A quick way to calculate your anticipated household hot water usage is to multiply the house occupants by 18 gallons. These calculations will enable you to gauge the collector and reserve tank required for keeping your house in hot water.

Two Types of Solar Water Heaters That you can Choose From:

  • Solar thermal – Solar thermal panels convert heat from sunlight into warm water for use in your house’s hot-water tanks or showers. The panels work by absorbing sunlight during the day and then releasing heat into your hot-water tank at night, or in cloudy weather, when there isn’t enough sunlight to generate enough energy for their use.
  • Solar electric – Like a traditional electric furnace, these units get electrical power from a utility company and use it to heat cold water stored in an underground storage tank (UST) or in a cistern on your property. You will still need an electric meter on your property because this unit won’t be able to produce enough hot-water energy to provide for your own needs.

Read More: Wind Power for Homes

Solar Water Heater Advantages

There are several advantages that come with using a solar water heater. We have listed some of the advantages below.

1. Little Maintenance

Unlike traditional water heaters, solar water heaters are essentially passive systems and require little or no maintenance. Nevertheless, replacing the circulated antifreeze fluid and the system surveyed by a contractor for safety precautions every few years is paramount. So, well-maintained solar water heaters are also expected to last decades while giving hot water with solar energy.

2. Save On Your Energy Bill

Installing a solar water heater will save your energy bills because solar power is free. Solar heaters use energy from the sun so that you won’t be paying a cent for the power usage.

3. Less Space

Solar water heaters take less space than traditional hot-water tanks since fewer panels are required to heat water. They are also different sizes of the storage tank and the solar heater.

4. Safe for the Environment

Using solar energy means a lower carbon footprint. Solar panels are eco-friendlier. Proponents of solar water heating systems say that they are an environmentally friendly technology because they prevent the release of carbon dioxide into the atmosphere.  

Solar panels are the best energy source since they produce zero emissions as the world tries to go green. So, anytime you use natural gas to heat your water at home, greenhouse gases are emitted into the atmosphere.

5. High Efficiency

Around 80 percent of the solar radiation is converted into heat energy required to obtain hot water in homes.

Solar Water Heater Disadvantages

Despite so many solar heater advantages, some demerits come with it. Below, we cover some of the disadvantages of solar hot water heaters.

1. The Climate

A solar hot water heater is entirely run by solar power. And therefore the amount of power generated per day will depend on the day’s climate. In short, your local climate is one of the significant factors to consider when establishing the workability of your solar hot water heater. Above all, you don’t require sun every day of the year for your solar to work. But to have more efficient solar power, you should use a solar heater in places that experience too much sunshine.

2. Maintenance

Understand that although most solar water heater systems do not need a high degree of maintenance, scaling arises when there are suspended minerals in domestic water. These minerals build up calcium deposits in the system.

Certainly to eliminate such problems, you may add mild acidic substances such as vinegar or water softeners to prevent scaling. You can do it every two to five years, depending on the quality of the water.

3. Acquisition Cost

Like many improvement projects at home, a solar water heater has high upfront costs. And so a complete hot water system will cost a lot of money even before you have figured out the contractor’s installation cost. This is especially true if they need unique setups such as the flat plate collector.

4. Solar Water Heater is Only Used for Water

Just as its name suggests, a solar water heater can only be used to heat water but cannot power your other electric appliances. To power the rest of your home appliances using solar energy, you will require installing a photovoltaic (PV) system that converts solar energy into electricity for your appliances.

5. Corrosion With Solar Water Heating

Oxygen can rust any steel or iron part in open loop hydronic solar systems. Also, the plumbing materials are more resistant if made of stainless steel, bronze, brass, rubber, or copper. To avoid corrosion, storage tanks should be fitted with plastic or glass.

6. Overheating

The active system of solar panels can overheat if there is a wrong storage tank size for the collector. The recommended standard is that there should be 1.5 gallons of storage for each square foot of collector.

Read More: Easy Definition of a Solar Inverter and its Working Principle.

Conclusion

The results of a solar water heater system mainly depend on the organization of the collector and the entire system design. The installation of a solar water heater depends on your location, climate, safety issues, and the amount of water you want to heat. After installation, proper maintenance of your system will ensure your system keeps running smoothly and for a long time.

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